import random

code = ''
code_num = 4
while True:
    for i in range(code_num):
        current = random.randint(0,code_num)
        if current == i:
            code += chr(random.randint(97,122))
        else:
            code += str(random.randint(0,9))
    if code.isdigit() or code.isalpha():
        code = ''
    else:
        print(code)
        code = ''
        break


